1. Field of the Invention
The present invention relates to additives for animal litter; and more particularly to an additive for cat litter, which releases an odor controlling or odor masking substance when the animal uses a litter-box.
2. Description of the Prior Art
Many commercial litter products contain a scent that either over powers the litter smell or simply has ingredients that mask the litter odor. The litter odor is highly objectionable especially in heated or air-conditioned closed rooms. In these products, the scent producing ingredient is incorporated within the cat litter and the scent from the scented litter is released all the time creating over powering smell in the closed room. This overpowering scent is the reason why many people prefer unscented litter and hope to clean the litter box promptly when the litter box is used by the animal. To aid this cleaning process litter compositions have been developed that clump when the litter box is used for urination thereby enabling the prompt easy cleaning of agglomerated clumps. Yet, the unscented litter progressively accumulates malodor and has to be replaced periodically.
Many patents disclose methods for control of odor in animal litter. When animal litter is not of a clumping variety, it is difficult to control the odor since the urine excreted is absorbed over a much larger distance. Clumps are created when the composition of the litter swells during the absorption of pet urine, creating a localized rigid clump. Typical additives for litter which provide this swelling action and urine absorption property include gypsum (calcium sulfate hemi-hydrate) which absorbs water, forming CaSO4.2H2O, swelling Kaolin or montmorillonite clays. Gums of different variety are also used to dissolve and form a bond, creating clumps. Odor control is generally achieved by adding ingredients to the litter that either mask the odor or add compounds that are anti-bacterial, or other compounds that exhibit pleasant smell.
U.S. Pat. No. 3,675,625 to Miller et al. teaches a litter which is “activated” by heating and then contacted with an odor control agent, such as pine oil, citrus oil, camphor or the like.
U.S. Pat. No. 4,203,388 to Cortigene et al. teaches the use of a deodorant such as sodium bicarbonate, in amounts of between about 1% and about 10% of the dry weight of the litter. Such large amounts of deodorizer are necessitated since the litter itself is also used as an absorbent for urine, requiring the deodorizer to be homogeneously dispersed throughout the particles of the litter.
U.S. Pat. No. 4,405,354 to Thomas et al. discloses the use of buffering agents to prevent gaseous ammonia from escaping into the air. However, such buffering agents serve only to prevent the formation of gaseous ammonia; they are ineffective against other unpleasant odors. Further, the amounts of such agents range from about 0.5% to about 25% by weight, since all of the absorbent litter must be treated with the agent to provide sufficient contact with the urine.
U.S. Pat. No. 4,459,368 to Jaffee, et al. discloses particulate sorbing and deodorizing mixtures containing synthetic and clay sorbents. The composition contains sorbent fuller's earth clay particles and sorbent synthetic particles, e.g. calcium sulfate dihydrate-containing granules, in a weight ratio of about 0.5:9.5 to about 4:6, respectively. This combination of clay minerals and calcium sulfate dihydrate does not provide odor control.
U.S. Pat. No. 4,517,919 to Benjamin et al. discloses the use of undecylenic acid in amounts from about 1000 to about 10,000 ppm and a bacteriostat in amounts from about 25 to 500 ppm. U.S. Pat. No. 5,094,190 to Ratcliff et al. teaches an odor control animal litter to which a boron-containing liquid material has been applied.
U.S. Pat. No. 5,097,799 discloses odor control agents selected from the group consisting of guanidine salts, alkali metal fluorides, alkali metal bisulfites, and mixtures thereof. These agents are applied to the litter using an aqueous dispersion to produce an odor control animal litter.
U.S. Pat. No. 5,183,655 teaches an odor control animal litter that has applied to it an effective amount of pine oil in combination with an effective amount of boric acid.
U.S. Pat. No. 5,329,880 to Pattengill, et al. discloses clumpable animal litter. This waterproof litter contains a mixture of non-smectitic, hydrophilic shale aggregate with a fraction of coarse material with a size less than about 5 mesh (4000 microns). The mixture has the property of agglomerating into a clump upon contact with urine. The agglomerated clump of shale and urine is removable with a perforated scoop. The shale may contain up to 10 weight percent clumping agent selected from the group of water absorbent polymers, corn starch, gelatin, gluten and dried plants of the Plantago family. In addition 5 to 25 wt % ammonia absorbing zeolite may be added for odor control. The odor control agent is an absorbent only for ammonia and does not provide odor control since ammonia is not immediately formed.
U.S. Pat. No. 5,634,431 to Reddy, et al. discloses odor inhibiting pet litter. The addition of urease negative bacteria to sodium smectite clay minerals in pet litter inhibits growth of urease positive bacteria for a period of several days, thereby retarding formation of ammonia and other obnoxious odors. Approximately fifty percent sodium bentonite in the litter causes the litter to clump upon wetting, maintaining the urea in contact with the treated clay and also serving as a buffer to favor growth of the urease negative bacteria. This composition entirely relies on inhibiting ammonia formation and does not provide immediately a pleasant scent.
U.S. Pat. No. 5,806,462 to Parr discloses clumping animal litter. The animal litter is particularly suited for cats. A gelatin solution and a dry adhesive is sprayed onto the granules. The gelatin solution provides enough dampening to adhere the adhesive particles to the clay particles. Because the gelatin sets quickly, it does not provide so much wetting as to activate the adhesive. Therefore, the adhesive retains its adhesive properties and, together with the gelatin, causes the litter to clump when wetted by an animal. This clumping cat litter formulation provides no odor control.
U.S. Pat. No. 5,975,019 to Goss, et al. discloses clumping animal litter. The clumping animal litter utilizes the interparticle interaction of a sodium bentonite, a swelling clay, with a non-swelling clay material. Preferably, sixty percent (60%) by weight, or less, composition of sodium bentonite is used after the judicious selection of particle size distribution such that the mean particle size of the non-swelling clay material is greater than the mean particle size of the sodium bentonite. In addition, an organic clumping agent, such as a pregelatinized corn starch can be combined with the sodium bentonite/clay mixture to enhance clumping properties. This clumping clay litter does not control odor.
U.S. Pat. No. 5,992,351 to Jenkins discloses clumpable animal litter with improved odor control. The clumpable animal litter with improved odor control comprises a) water-swellable clay particles capable of adhering other such particles upon contact with moisture; and b) an odor controlling-effective amount of a boron compound of a composition di-alkali metal tetraborate n-hydrate, wherein n is 4, 5 or 10, which controls odors arising from the contact of said clay particles with moisture.
U.S. Pat. No. 6,206,947 to Evans, et al. discloses a process for making an animal litter comprising gypsum, aluminum sulfate and urea. The animal litter composition is an agglomerated or compacted calcined calcium sulfate absorbent. The animal litter composition is screened to a particle size between 6 mesh and about 100 mesh and an effective amount of a binder such as a clay, lignin or starch is added to the calcium sulfate to assist the calcium sulfate to pelletize. This is a gypsum composition that is agglomerated using aluminum sulfate and urea to chemically combine with gypsum. There is no odor control in this clumping litter composition.
U.S. Pat. No. 6,253,710 to Ward, et al. discloses odor control for animal litter. It uses an odor control liquid and an aerosolized composition for deodorizing and controlling the odor of animal wastes. The liquid and aerosolized composition comprises a non-aqueous volatile carrier and an odor control agent. The liquid and aerosolized composition can be applied in liquid form directly to the animal litter and/or the animal container and/or the animal waste. The litter container may be sprayed with a powdered release agent which may be talc, of talc, inorganic silicone and magnesium powders, sodium bicarbonate, chlorophyll, sodium dihydrogen phosphate, potassium acid phthalates, or their mixtures preventing the stickiness of the odor controlling liquid. The liquid mixes with the litter product and constantly evaporates. Consequently, the odor control agent continuously disseminates and becomes quickly exhausted.
Number of prior art patents relate to micro encapsulation of fragrances and these fragrances are continually released. Some of the patents disclose encapsulation wherein the fragrance is prevented from slow release by having an impervious cell wall.
U.S. Pat. Nos. 6,375,983 and 6,558,706 to Kantor, et al. discloses microencapsulated fragrances and method for preparation. This encapsulated fragrance has a microcapsule from which the fragrance is controlled can be released by exposing the encapsulated fragrance to a solution of a predetermined pH. The encapsulant for the microcapsule is a copolymer of acrylic acid monomer and a one ethylenically unsaturated polymerizable monomer. The copolymer further comprises a pH sensitive carboxyl group or an amine group. The microcapsule encapsulant dissolves when it contacts a solution of appropriate pH. This encapsulated fragrance is not indicated to be usable in a litter.
U.S. Pat. Nos. 6,375,983 and 6,558,706 to Kantor, et al. disclose microencapsulated fragrances and method for preparation. This encapsulated fragrance has a microcapsule from which the fragrance is controlled can be released by exposing the encapsulated fragrance to a solution of a predetermined pH. The encapsulant for the microcapsule is a copolymer of acrylic acid monomer and a one ethylenically unsaturated polymerizable monomer. The copolymer further comprises a pH sensitive carboxyl group or an amine group. The microcapsule encapsulant dissolves when it contacts a solution of appropriate pH. This encapsulated fragrance is not indicated to be usable in a litter.
U.S. Pat. No. 6,369,290 to Glaug, et al. discloses time release odor control composition for a disposable absorbent article. This disposable absorbent article is provided with a odor control powder which is unscented in a dry state and releases a burst of fragrance when wetted, such as by human waste. The powder contains a relatively small amount of fragrance oil, such as 0.5% to 4% by weight, to prevent skin irritation to the wearer. The small amount of fragrance oil is microencapsulated in a starch, which constitutes from about 50% to 90%, and preferably about 70%, of the total weight of the particles. Sodium bicarbonate is also included in the particulate odor control material in an amount ranging from 5.0% to 45%, and preferably about 25% by weight, of the total weight of the particles. The sodium bicarbonate promotes skin wellness by controlling the pH levels of the fragrance oil, starch and human waste. A small amount of flow agent is also contained in the particulate odor control material. The odor control composition is indicated to be used in a disposable absorbent article for absorbing and containing body fluids, comprising an absorbent core and an odor control powder, both located between a fluid pervious cover sheet and a fluid impervious or hydrophobic backing. The odor control powder is substantially unscented when in an initial dry condition, before being wetted, and is capable of releasing a mild fragrance when wetted. The composition is not indicated to be usable in an animal litter.
U.S. Pat. Nos. 6,638,591 and 6,902,817 to Bowen, et al. discloses membrane permeable to aromatic products. This multilayer structure with improved permeation for atmospheric diffusion of aromatic products has a structure with a first permeable layer of a blend of very low density polyethylene and low density polyethylene, a second permeable layer of low density polyethylene, a third permeable layer of a blend of very low density polyethylene and low density polyethylene, a fourth permeable layer of a material selected from a blend of low density polyethylene and a modified polyolefin and a release layer comprising ethylene vinyl alcohol copolymer. The multilayer wall structure of a close extruded cell releases aromatic compound at a slow rate.
U.S. Pat. No. 7,235,261 to Smith, et al. discloses a controlled release encapsulation. The controlled release encapsulated dry powder is formed by an emulsion having a fully hydrolyzed polyvinyl alcohol polymer, a hydrophobic silica, a modified corn starch, and a fragrance oil. The fragrance oil is emulsified in water and spray dried to evaporate the water obtaining the encapsulated dry powder. The dry powder with encapsulated fragrance oil provides controlled release of the fragrance, presumably due to cracks and irregularities present in encapsulation wall.
There remains a need in the art for a cat or animal litter composition containing ingredients that release a pleasant scent only after the cat or animal uses the litter. Also needed in the art is an animal litter composition that does not overpower the environment with litter scent. Further needed is an animal litter composition that eliminates the malaise odor of common litter boxes.